import cv2

import numpy as np



def watershed_algorithm(image):

    # 转换为灰度图像

    gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)

    # 二值化

    _, binary = cv2.threshold(gray, 0, 255, cv2.THRESH_BINARY + cv2.THRESH_OTSU)

    # 查找轮廓

    contours, _ = cv2.findContours(binary, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)

    # 计算轮廓面积

    areas = [cv2.contourArea(c) for c in contours]

    # 按面积排序

    areas.sort()

    # 初始化分水岭

    watershed = np.zeros_like(image)

    # 遍历轮廓

    for area in areas:

        # 找到最大轮廓

        max_area = max(areas)

        for i in range(len(areas)):

            if areas[i] < max_area:

                break

        # 找到最大轮廓对应的轮廓

        max_area_index = i

        # 找到最大轮廓的边界框

        x, y, w, h = cv2.boundingRect(contours[max_area_index])

        # 在原图上绘制分水岭

        watershed[y:y+h, x:x+w] = 1

    return watershed



# 读取图片

image = cv2.imread('input.jpg')

# 应用分水岭算法

watershed = watershed_algorithm(image)

# 显示结果

cv2.imshow('Watershed', watershed)

cv2.waitKey(0)

cv2.destroyAllWindows()